text: var fs = require ("fs");
  var XLSXChart = require ("./../chart");
  var xlsxChart = new XLSXChart ();
  var opts = {
  	titles: [
  		"Title 1",
  		"Title 2",
  		"Title 3",
  		"Title 4"
  	],
  	fields: [
  		"Field 1",
  		"Field 2",
  		"Field 3",
  		"Field 4"
  	],
  	data: {
  		"Title 1": {
  			"chart": "column",
  			"Field 1": 5,
  			"Field 2": 10,
  			"Field 3": 15,
  			"Field 4": 20
  		},
  		"Title 2": {
  			"chart": "bar",
  			"Field 1": 10,
  			"Field 2": 5,
  			"Field 3": 20,
  			"Field 4": 15
  		},
  		"Title 3": {
  			"chart": "line",
  			"Field 1": 20,
  			"Field 2": 15,
  			"Field 3": 10,
  			"Field 4": 5
  		},
  		"Title 4": {
  			"chart": "area",
  			"Field 1": 10,
  			"Field 2": 5,
  			"Field 3": 20,
  			"Field 4": 15
  		}
  	},
  	chartTitle: "Column, bar, line and area chart"
  };
  xlsxChart.generate (opts, function (err, data) {
  	if (err) {
  		console.error (err);
  	} else {
  		fs.writeFileSync ("mix.xlsx", data);
  		console.log ("mix.xlsx created.");
  	};
  });
  